The present invention relates to apparatus and a process for the wet-processing, especially dyeing, of textile material by the exhaust method at a short liquor ratio in a very short time.
The currently most widely used method for dyeing circular knits is in jet machines by exhaust methods. In this technology, the textile material, gathered into a rope on a lot- or piecewise basis, is transported by a jet nozzle with treatment liquor, with air/steam or with a combination of the two media into a scray. The main feature of this processing technology is that the textile material in endless form is conveyed through the machine by the kinetic energy of the tangential jet, it being possible for gas and liquid flow to alternate or be combined during the different treatment stages, which permits a seamless transition from one dyeing step to another without a standstill of the material and under isothermal conditions.
For instance, EP-A 0 014 919 discloses an isothermal treatment process wherein the hot, preheated substrate is contacted with hot treatment liquor in a conventional jet machine by feeding one part of the treatment liquor to the scray space and the other to the jet nozzle and propelling the fabric selectively by means of a gas or by means of a liquid (i.e., the liquor) or by means of both together.
EP-A-0 078 022 describes a discontinuous dyeing method which is based on the aerodynamic propulsion of the textile rope and in which the fiber material is introduced into the dyeing jet in the form of batches. In the dyeing jet, the dyeing liquor is applied to the material by injecting it into the circulating gas stream in atomized form, each time giving fresh impetus to the circulation of the textile material and of the treatment liquor not absorbed by the material. The application of the total liquor quantity takes place over a plurality of circulations of the material, and the continuous recirculation of the excess liquor ensures uniform distribution of the liquor not only on but also in the rope. When the dyeing operation has ended, the piece-dyed material is removed again from the jet. This process is carried out in a jet machine of the conventional design, which is provided with additional means for spraying or atomizing the treatment agent into the propulsive gas stream.
The disadvantages of the cited processes include, for example, that purely cellulose articles still require the use of a relatively long liquor within the range from 6:1 to 8:1 and that it is therefore necessary to expend considerable quantities of thermal energy to heat these liquor quantities to the required temperatures. In addition, in these processes, the jet machine inevitably contains large amounts of excess, freely circulating liquor, so that the fabric is in contact with the liquor throughout the entire machine, even in the scray. The consequence of this is a relatively long exhaustion process for the dye and an even longer metering and fixing process.
There has therefore been no shortage of attempts to modify the application conditions for the colorant in such a way that a uniform dyeing may be obtained with ideally a single, ideally minimal, liquor application. For instance, EP-A 310013 describes a process for the continuous dyeing of textile material in rope form by means of jet machines in which the propulsive drive for the transportation of the material is supplied by the kinetic energy of a recirculating gas stream through the agency of the jet system. In the course of this dyeing process, the gas stream from the jet nozzle has continuously sprayed into it a dyeing liquor which already contains all the assisting chemicals required for fixing the dye. The liquor quantity is such that the entire applied liquor remains in the rope and there is no occurrence of excess, migrating liquor even during the subsequent fixation. However, this process is technically not implementable for reactive dyes, for example, ultimately for two reasons:
1. The marks produced during the single application of dye never level out in the further course of the isothermal process described, contrary to the statements in the reference. Since the dye solution already contains all the chemicals necessary for fixing reactive dyes, the fixing process starts immediately after the isothermal impregnation. During the continued transportation by the gas or gas/steam mixtures, no further migrating liquor is available for any leveling, and any unlevelness, once produced, is no longer evened out.
2. During the aerodynamic transportation of the rope by a thermally treated gas, applied dye solution is blown about, which causes local concentration differences and consequent unlevelness on the dyed material.
It is an object of the present invention to provide apparatus and a process which is free of the disadvantages mentioned and which affords dyeings of high quality with very short liquor ratios and within a very short time.
It has now been found that, surprisingly and contrary to a widely established view among those skilled in the art, it is possible for a textile rope material to be impregnated with level results in a jet transportation means in a very short liquor, for example with reactive dyes in a liquor ratio of 3:1 within only three to seven circulations, and to apply the necessary fixing alkali in additional 0.5 fabric weight units in the same apparatus in the continued process, i.e., for it to be dyed without incurring any unlevelness or marking on the textile material.
The present invention accordingly provides apparatus for the wet-processing of textile material, essentially comprising a vessel (1) comprising a fabric inlet (2), at least one nozzle (3) for applying a treatment liquor, which nozzle may also be the fabric inlet, an intensive zone (4) and a fabric outlet (5), wherein said vessel does not include a scray and has a minimized dead space through accurate fitment of said nozzle (3) and said intensive zone (4) into said vessel (1).
The present invention further provides a process for the wet-processing of textile material in apparatus according to the invention. The apparatus according to the invention enables textile fabric ropes to be wet-processed essentially just through a consistent separation of liquor stream and fabric stream after each passage through the apparatus of the invention.
The wet-processing of textile material for the purposes of the present invention is to be understood as meaning in particular the dyeing of natural or synthetic textile materials with textile dyes and the associated pre- and aftertreatment. The apparatus and process of the invention provide advantageous dyeings with water-soluble dyes on circular knits, especially circular knits and wovens composed of natural or modified hydroxyl-containing or natural, modified or synthetic carboxamido-containing fiber materials.
Hydroxyl-containing fiber materials are for example cellulosic fiber materials, such as the natural fiber materials, like cotton, jute and linen, and the modified fiber materials produced from cellulosic natural materials, like regenerated cellulose, for example filament viscose rayon, and cellulose fibers modified with amino-containing compounds, as are known for example from U.S. Pat. Nos. 5,507,840, 5,565,007 and 5,529,585, from EP-A 665311 and from DE-A 19519023.
Carboxamido-containing fiber materials are natural fiber materials, such as wool and other animal hairs, and also silk, and synthetic polyamide fiber materials, such as fiber materials composed of nylon-6, nylon-11 and nylon-6,6.
Water-soluble dyes are especially those which are anionic in nature, for example the so-called acid and direct dyes, but especially fiber-reactive dyes. As fiber-reactive dyes there may be mentioned in particular those where the fiber-reactive radical is a radical of the vinyl sulfone series, for example vinylsulfonyl or an ethylsulfonyl group which is substituted by an alkali-eliminable substituent in the xcex2-position, such as xcex2-sulfatoethylsulfonyl, xcex2-acetoxyethylsulfonyl, xcex2-chloroethylsulfonyl or xcex2-thiosulfatoethylsulfonyl, also fiber-reactive radicals of the chlorotriazinyl, fluorotriazinyl, fluoropyrimidinyl, chlorofluoropyrimidinyl and dichloroquinoxazinyl series, and also dyes possessing combinations of such reactive groups. Fiber-reactive dyes of the kind mentioned are known to the person skilled in the art and are described for example in EP-A 513656.
The apparatus and the dyeing process of the invention can be used for treating all customary circular knit articles, such as single jersey, loop plush, interlock, fine rib, piquxc3xa9 and lining fabrics. In addition, the wet-processing of wovens is readily possible under the conditions of the invention.
In addition, however, it is also possible, if necessary with some modifications or configuration as HT apparatus, to dye textile material composed of polyester with disperse dyes or textiles composed of other materials with dyes appropriate for these materials.
The pre- and aftertreatments of the textile material which accompany the actual dyeing and which are likewise effected with the aid of the apparatus of the invention are in particular treatments for applying finishes, but primarily bleaching and washing processes.
The apparatus and dyeing process of the invention is used with particular preference for the dyeing of cellulosic circular knits and wovens with reactive dyes and the associated pre- and aftertreatments of the textile material.
The vessel (1) of the apparatus of the invention can in principle have any desired geometric shape, but is preferably cylindrical or cuboid. Owing to the absence of a scray and the accurate fitment of nozzle (3) and intensive zone (4), the vessel (1) has very small dimensions compared with customary dyeing jet machines and has a cubic capacity of advantageously less than 150 liters. Particularly preferably, its cubic capacity is 60 to 120 liters.
The fabric inlet (2) and fabric outlet (5) normally take the form of the customary dyeing jet entry and exit elements, which also serve as pressure seals in the case of HT processes. Such elements are well known to the person skilled in the art and are described for example in DE-A 2537665 and DE-A 2325604. The fabric outlet (5) is preferably connected to a wiping means, for example a rubber lip, a metal ring or a conical cylindrical segment, or already configured as such. The nozzle (3) is normally likewise a customary dyeing jet component which is constructed in such a way that it is driven hydraulically with flowing liquor by means of a pump (6) to provide forward drive and simultaneous impregnation of the textile material. The forward drive can be additionally supported by other means which the person skilled in the art knows for this purpose, for example winches or air jets.
The intensive zone (4) will usually be a cylindrical metal tube in which the material to be treated is additionally in intensive contact with the treatment liquor for a short time.
The vessel (1) preferably has at the lowest position of its underside one or more openings (7) through which the excess liquor can run off and is preferably recirculated back to the nozzle (3). It is particularly preferable for the vessel (1) to be perforated on its underside for this purpose.
As and when required, the apparatus of the invention may have further constructional elements, for example a fluff filter. If polyester is to be dyed with disperse dyes, the apparatus of the invention has to be for example equipped with appropriate heating means to provide the temperatures required for this purpose. There is generally also a need for makeup vessels for the liquor or other treatment liquids, and also for the corresponding feed and discharge lines, pumps and, as the case may be, heat exchangers. It is also advisable for that part of the fabric rope which is not passing through the apparatus of the invention to be plaited down in an intermediate store, or scray, placed suitably alongside the apparatus of the invention.
It is possible to construct the apparatus of the invention in such a way that the jet nozzle (3) also acts as fabric inlet (2).